That's really weird because Rina/Roa's tend to be built rather well. It shouldn't be peeling apart after only 4-5 uses. What lube/lubes do you use? Soap brand? I have 2 dual layered holes now (Mouth of Truth and Wonder Ring Poco Pen which is a hip). Only thing that I noticed with mine is that the initial break in period seemed to have some of the inner flesh breaking off like it was just left over from when the toy was molded and didn't get completely/thoroughly washed or whatever afterwards.
The stickiness you feel could just be the inner flesh, though again with out knowing what lube you are using and soap brand, it's kind of hard to tell if that could be the cause as soem toys don't react well with certain kinds of soap and lube and have been known to cause some form of deformations such as the inside rubber/flesh becoming a goo and/or causing it to become very fragile and come apart.
As AkaiHebi says in his post >>628
glue between the layers should work if the inner sleeve ever comes out or undone as unlikely as that has been. As well as the toys becoming defunct after a while of usage, though your case of -45 times of use and it's having a problems seems off. Could either be a bad mold or as I said above the lube and or soap brand. Have had my Lube react differently in my Mouth of Truth and my WRPP. Luckily my soap (Lever 2000 brand) seems to work well on both and not be destructive the the materials.
Sorry for text walls and hope this helps!